This invention relates to a laboratory device for mixing a volatile substance while simultaneously preventing any harmful or obnoxious vapors from escaping into the surrounding environment. Specifically this invention is primarily related to laboratory device for preparing an acrylic bone cement from methylmethacrylate monomer and poly(methylmethacrylate) wherein the components can be manually or mechanically mixed without danger of the monomer vapors escaping into the atmosphere, typically a hospital operating room.
Recently, the Food and Drug Administration approved the use of methyl methacrylate acrylic cement for general clinical use in orthopedic surgery. Since that time bone cement based on methyl methacrylate monomer and poly(methyl methacrylate) has received wide popularity.
The bone cement components are mixed by the surgeon or an assistant in the operating room just prior to use to form a pasty material in a well known manner. The pasty bone cement can then be used for such applications as anchoring prostheses, e.g. femoral hip prostheses in bone.
However, as reported in an article entitled, "Acrylic glue component poses hazard" appearing in JAMA, Nov. 27, 1972, Vol. 222, No. 9 methyl methacrylate monomer "can depress heart and lung function, can cause serious damage to lung tissue, and - in high cencentration - can cause death" when not properly used. These critical problems can be avoided, it is reported, by evaporating excess monomer (monomer not used in the bone cement) by prolonging aeration and mixing time of the cement reactants. The monomer, however, should not be allowed simply to evaporate into the operating area since it has a generally unpleasant odor and can be harmful to the operating room personnel. In addition, the methyl methacrylate monomer is flammable, thus posing another serious problem.
While the mixing can be performed under a hood which is vented to the outside this approach necessitates modification of the existing operating room system and is therefore not satisfactory. It has also been proposed to use a covered mixing bowl which can be connected to the existing operating room vacuum system. However, to date, no entirely satisfactory portable, lightweight, reuseable and inexpensive device has been developed which readily permits for manual mixing and substantially complete aeration of the reactants while simultaneously drawing off harmful or obnoxious vapors and preventing their escape into the operating room.